Prisoner's Return is First in 2014, Reducing Population to 154

WASHINGTON—The Obama administration said Thursday it had repatriated a Guantanamo detainee to Algeria, reducing to 154 the population of a prison that has held nearly 800 men since January 2002.

The move comes amid halting efforts by the U.S. to transfer detainees from the prison on a naval base in Cuba and eventually shutter it. President Barack Obama last year renewed his commitment to closing Guantanamo after a monthslong detainee...